Page 39 - Power Electronics Handbook

32 Power semiconductor devices

- Emitter
contact

Base
CoMBc1

Eminer
/ contact
Emitter
diffusions

Base
- contact

(6)
1.15 High-frequcncy transistor geometries: (a) interdigitated; (b) oveday

Unipolar transistors are also known as field effect transistors (FET) and
they are capable of several different operation modes, as illustrated in
Figure 1.16. The junction field effect transistor (JFET) can have ap or an n
channel, but it can only operate in depletion mode, as explained later. The
metal oxide semiconductor field effect transistor (MOSFET) can also be p
or n channel, and both these may be designed to operate in enhancement
or depletion mode.

Unipolar transistor (FET)
n channel Gl , pcha,nnel r-l , nchjnnel ,
,
MOSFET

(depletion) p channel
(depletion)

Depletion Enhancement Depletion Enhancement
Figure 1.16 Unipolar transistor variations